Nike CEO Mark Parker is known for constantly questioning his employees to push them to think harder. Research shows that leaders who ask questions and encourage employees to find answers themselves are more effective than those who try to have all the answers. Parker's style reflects that of a "multiplier" leader, who believes abilities can be cultivated. Multipliers tend to lead twice as productive teams as "diminishers" by prompting employees to solve problems, boosting self-efficacy. Parker acknowledges inquisitiveness supports development and ensures people challenge existing ways of thinking.